Talk about a comedown. What had previously been a sedan we’d regularly praised — and GM’s best-selling car — finished dead last. How could the likable Malibu have fallen so far? Mostly this: a retrograde interior, a nearly useless rear seat, and the thirstiest powertrain in our group.

“The back seat is too small for passengers with legs,” logs associate online editor Christian Seabaugh. … Such is the penalty served by Chevy slicing 4.5 inches out of the new Malibu’s wheelbase. (The roomy sedan in the lineup will be the 2014 Impala.) Also drawing jabs was the general look of the interior, a curious, quasi-steampunk mix of football pigskin leather, cheesy faux wood, and glitzy chrome accents. The LTZ’s standard leather seats also took a beating for being “rock hard” and “flat”–with “no support at all.” Most of our team praised the MyLink touch screen, however, noting its ease of use and general cool factor.

The chassis rides well, but after that the praise ends. Steering feel is simply lousy — zero feedback, and you’ll find yourself working the wheel even on arrow-straight highways. The soft suspension, writes Evans, means “seesaw action over bumps.” Febbo is less charitable: “No confidence in the chassis.” The new Malibu offers nothing to the enthusiastic driver. …

Seabaugh sums it up bluntly: “Unusable at its most basic function — family sedan.”

GM has announced a hurried “mid-cycle refresh” after only 18 months, confirmation that the now-degraded Malibu needs an emergency rescue. (Honda recently performed a similar rescue on the much-panned Civic. The difference is that the Civic, unlike the Malibu, continued to sell well even as it displeased the critics.)

OK. But who screwed up the ‘Bu? A corporate orgy of recrimination would seem to be in order. Was the flawed design a product of Obama’s New GM? That’s not clear–“New GM” was born in 2009, and the car came out in 2012. Three years would be a very quick product cycle–though many parts, like suspension bushings, can clearly be changed closer to the release date. Current CEO Dan Akerson apparently rushed the launch of the Malibu’s “eco” edition–but did that make it bad?

Ordinarily, we would have little chance of finding out what happened and who, exactly, is to blame–GM’s business would be GM’s business (and it’s very hard for even experienced reporters to uncover the truth about the company). But this case is different. U.S. taxpayers bailed General Motors out and still own a quarter of it. GM’s been blowing our money here, and its Malibu screw-up is depressing the value of our stock. We have more of a right than usual to know who did it and why.

Where is Rep. Issa when you need him?

P.S.: Chevrolet, which is GM’s biggest division, seems to have actually sold fewer cars in November, 2012 than in November, 2011, even though the overall auto market grew. So far this year, GM sales are up 4% when the average of all manufacturers is an increase of 14%. That means a fairly significant decline in market share. …